When I fix my paper for gum printing on a rigid substrate for re-registration, as I do for larger formats, I use a hot water bath to remove the print from the substrate, and this procedure necessitates varnishing it first, or otherwise part of the colour softens and dissolves in the hot water.
I use glossy or semi-matte varnish, and both definitely and considerably improve shadow values in particular, and the richness of colours. Therefore I think varnishing a gum print with an archival varnish is quite recommendable, and the same goes for iron-salt processes. I don't do it always, not even often, for it is quite extra work, and the character of the print certainly changes, but tonal values improve, and the print does not lose its hand-made quality.

04-06-2009, 12:07 PM

Loris Medici

Lukas, exactly which varnish (type, composition, brand?) do you use for your gum prints? I was using Hydrocote Polyshield non-yellowing exterior polyurethane wood varnish for iron prints, I plan to try it for gum prints soon... Learning about other options would be nice.

Thanks in advance,
Loris.

04-07-2009, 07:30 AM

Lukas Werth

Quote:

Originally Posted by Loris Medici

Lukas, exactly which varnish (type, composition, brand?) do you use for your gum prints? I was using Hydrocote Polyshield non-yellowing exterior polyurethane wood varnish for iron prints, I plan to try it for gum prints soon... Learning about other options would be nice.

Thanks in advance,
Loris.

Loris,
I would like to answer your question fully, but there is a problem: I recently shifted my residence from Germany to Lahore, Pakistan, and I have to admit that parts of my printing stuff is still wating t be taken out from the boxes and ordered. I hope, however, to resume gum printing pretty soon, by which time I will be forced to sort out my stuff, and accordingly be able to tell you the brand name. It is an acrylic varnish from a Dutch company, bought from a German art supplyer (Boesner). I cannot find it on their website, however.
It is acidic, so I used it successfully to varnish cyanotype (gum over cyano, actually).

But would you enlighten me about "iron prints"? Are you referring to cyanotypes or something else, not-blue?

Iron prints -> Cyanotype*, Vandyke/Kallitype/Argyrotype*, Pt/Pd*, Chrysotype... (* denotes those I used for making prints)

Best,
Loris.

04-21-2009, 01:00 PM

q_x

Shine or glossy

Some things will look better with glaze finish, some like matte more? Is it not all this way?

I always loved to print pigment rich thick 1-2 layer gums on non-seized paper (cheap acid-free Canson 120-200 g/m2). Later, after short exposition, I was developing prints with airbrush or "something stronger" (finger on the end of pipe is quite efficient water spray). This method destroyed all finest details and all tonal small things, but results was good enough (with subjects like ruined houses or some train landscapes), 100% matte prints.

If you start printing from pigment-reach surfaces, ending with almost pure gum layers for lights you'll get more glaze, that is my experience. Why not use gum solution to make glossy finish? Also addition of starch or fine diatomaceous earth or lots of pigment in gum will produce matte surface.

04-21-2009, 04:10 PM

Katharine Thayer

Quote:

Originally Posted by q_x

If you start printing from pigment-reach surfaces, ending with almost pure gum layers for lights you'll get more glaze, that is my experience. Why not use gum solution to make glossy finish?

That's an interesting idea, that I'm not sure I've heard before, to end with a pure gum solution to glaze the print with a glossy coat. The gum would need to be mixed with dichromate and exposed like any other gum layer, in order to harden the gum (unhardened gum remains highly water-soluble forever), and chances are you'd get a dichromate stain that would need to be cleared so as not to sully the appearance of the print. I'd think it would be a whole lot easier, if you want a gloss finish on a gum print, to follow some of the earlier suggestions in this thread for using varnish, or I would think an acrylic medium, or that Gamblin PVA, would also be options for this.
Katharine

04-21-2009, 05:13 PM

sdivot

Katharine is right. You do get a stain. A layer of plain gum on top of everything will give you a tan color on your print. If you want an aged look, I think it would work well. On my website I have two identical images from my Italy (Italy #31) portfolio. One has a top coat of plain gum. You can see it put a tan-ish tint on it.
Stevewww.scdowellphoto.com